JP7013914B2 - Liquid discharge head, liquid discharge unit, and device that discharges liquid - Google Patents

Description

The present invention relates to a liquid discharge head, a liquid discharge unit, and a device for discharging a liquid.

Regarding the liquid discharge head used in printers, facsimiles, copying machines, etc., it has a nozzle for discharging liquid, a pressure chamber through which the nozzle communicates, and an electromechanical conversion element such as a piezoelectric element for pressurizing the liquid in the pressure chamber. Things are known. Further, two types of liquid discharge heads have been put into practical use, one using an actuator in a longitudinal vibration mode and one using an actuator in a deflection vibration mode.

As a method using the deflection vibration mode, for example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is cut into a shape corresponding to a pressure chamber by a lithography method. It is known that an electromechanical conversion element is formed independently in each pressure chamber.

In some liquid discharge heads having such a configuration, a groove is formed on the surface of the flow path substrate on the nozzle substrate side. For example, Patent Document 1 describes a nozzle substrate having a nozzle opening, a flow path substrate forming a liquid flow path including a pressure chamber communicating with the nozzle opening in a bonded state with the nozzle substrate, and a part of the pressure chamber. A liquid injection head provided with a pressure generating source that changes the volume of the pressure chamber by deforming the vibrating plate that partitions the pressure chamber, and droplets on both sides of the pressure chamber in the rowing direction in the flow path substrate. A liquid injection is provided with a dummy pressure chamber that does not participate in the discharge of the liquid, and a relief groove for introducing excess adhesive when joining the nozzle substrate and the flow path substrate in the region outside the liquid flow path. The head is disclosed.

However, when the groove is provided on the end side of the pressure chamber in the arrangement direction, the electricity on the end side close to the groove depends on the bending method and the amount of bending (hereinafter, also referred to as the degree of bending) of the diaphragm at the position where the groove is formed. It was found that it affects the degree of bending of the diaphragm at the formation position of the mechanical conversion element. As described above, if the degree of bending of the diaphragm varies among the electromechanical conversion elements, the discharge performance of the liquid discharge head is affected.

Therefore, an object of the present invention is to provide a liquid discharge head capable of suppressing the occurrence of variation in the degree of bending of the diaphragm between electromechanical conversion elements and obtaining good discharge performance in a configuration having a groove portion. ..

In order to achieve such an object, the liquid discharge head according to the present invention includes a pressure chamber forming substrate formed by arranging a plurality of pressure chambers for liquid discharge communicating with a plurality of nozzles for discharging liquid in a predetermined direction, and the pressure. An electromechanical conversion provided on the side of the chamber forming substrate opposite to the nozzle side, and a part thereof is provided on the vibrating plate layer corresponding to each pressure chamber and the vibrating plate layer constituting the wall surface of the pressure chamber. The pressure chamber forming substrate comprises an element, and a groove having a surface on the nozzle side opened is formed on the end side of the pressure chamber in the predetermined direction, and the vibrating plate layer on the pressure chamber is formed. The vibrating plate layer on the groove is formed by bending toward the pressure chamber side, and the vibrating plate layer on the groove is formed by bending toward the opening side of the groove, and the degree of bending of the vibrating plate layer of the pressure chamber is the vibrating plate of the groove. It is larger than the degree of flexure of the layer .

According to the present invention, in a configuration having a groove portion, it is possible to suppress the occurrence of variation in the degree of bending of the diaphragm between the electromechanical conversion elements and obtain good ejection performance.

It is sectional drawing which illustrates the liquid discharge head. It is sectional drawing which illustrates the manufacturing process of a liquid discharge head. It is sectional drawing which illustrates the liquid discharge head. It is a figure which illustrates the wiring and the like of a liquid discharge head. It is a figure explaining the bending of a diaphragm. It is a figure explaining the definition of the bending amount of a diaphragm. It is sectional drawing which illustrates the liquid discharge head which provided the groove. It is sectional drawing which illustrates the liquid discharge head which provided the groove. It is sectional drawing which illustrates the liquid discharge head which does not form a groove. It is a graph which shows the bending amount of 1 to 20 channels from the end part of a drive channel, and the bending amount of a diaphragm in 40 channels and 80 channels from an end part. It is explanatory drawing which shows the formation position of a groove and the radius of curvature of a diaphragm in a drive channel. It is explanatory drawing which shows the formation position of a groove and the bending amount of a diaphragm in a drive channel. It is sectional drawing and the plan view which exemplify the liquid discharge head provided with a groove. It is a top view which illustrates the liquid discharge head. FIG. 3 is a cross-sectional view and a plan view illustrating a liquid discharge head provided with a groove and a dummy channel. It is sectional drawing which illustrates the liquid discharge head provided with the groove and the dummy channel. It is sectional drawing and the plan view which exemplify the liquid discharge head provided with the groove of a non-penetrating shape. It is sectional drawing which illustrates the liquid discharge head which provided the groove. It is a plane explanatory view of the main part of an example of the apparatus which discharges a liquid. It is a side side explanatory drawing of the main part of an example of the apparatus which discharges a liquid. It is a plane explanatory view of the main part of another example of a liquid discharge unit. It is a front explanatory view of another example of a liquid discharge unit. It is a figure explaining the holding substrate. It is a figure exemplifying.

Hereinafter, the configuration according to the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 23.

(Liquid discharge head)
[First Embodiment]
<Construction of liquid discharge head>
FIG. 1 is a cross-sectional view of the liquid discharge head 1 showing an embodiment of the liquid discharge head. The liquid discharge head 1 has a substrate 10, a diaphragm 20, an electromechanical conversion element 30, and an insulating protective film 40 (first insulating protective film). Further, the electromechanical conversion element 30 has a lower electrode 31, an electromechanical conversion film 32, and an upper electrode 33.

In the liquid discharge head 1, the diaphragm 20 is formed on the substrate 10, and the lower electrode 31 of the electromechanical conversion element 30 is formed on the diaphragm 20. Further, the electromechanical conversion film 32 is formed in a predetermined region of the lower electrode 31, and the upper electrode 33 is further formed on the electromechanical conversion film 32. The insulating protective film 40 covers the electromechanical conversion element 30. The insulating protective film 40 has an opening that selectively exposes the lower electrode 31 and the upper electrode 33, and wiring can be routed from the lower electrode 31 and the upper electrode 33 through the opening.

A nozzle plate 50 provided with a nozzle 51 for ejecting ink droplets is bonded to the lower portion of the substrate 10. The pressure chamber 10x (sometimes referred to as an ink flow path, a pressurized liquid chamber, a pressurized chamber, a discharge chamber, a liquid chamber, etc.) communicating with the nozzle 51 by the nozzle plate 50, the substrate 10, and the diaphragm 20 is provided. It is formed. The diaphragm 20 forms a part of the wall surface of the pressure chamber 10x. In other words, the pressure chamber 10x is partitioned by the substrate 10 (constituting the side surface), the nozzle plate 50 (constituting the lower surface), and the diaphragm 20 (constituting the upper surface), and communicates with the nozzle 51.

In order to manufacture the liquid discharge head 1, first, as shown in FIG. 2, the diaphragm 20, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are sequentially laminated on the substrate 10. After that, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are etched into a desired shape and covered with the insulating protective film 40. Then, an opening is formed in the insulating protective film 40 to selectively expose the lower electrode 31 and the upper electrode 33. Then, the substrate 10 is etched from below to form a pressure chamber 10x. Next, the nozzle plate 50 having the nozzle 51 is joined to the lower surface of the substrate 10, and the liquid discharge head 1 is completed.

Although only one liquid discharge head 1 is shown in FIG. 1, in reality, as shown in FIG. 3, a liquid discharge head 2 in which a plurality of liquid discharge heads 1 are arranged in a predetermined direction is manufactured. The liquid discharge head 2 has a structure (liquid discharge head 1) including a nozzle 51 for discharging liquid, a pressure chamber 10x with which the nozzle 51 communicates, and a discharge driving means for boosting the liquid in the pressure chamber 10x. It is a structure in which a plurality of pieces are arranged in a predetermined direction. Here, the discharge driving means can be configured to include a diaphragm 20 forming a part of the wall of the pressure chamber 10x and an electromechanical conversion element 30 provided with an electromechanical conversion film 32.

Further, in the liquid discharge head 2, the portion of the liquid discharge head 1 (pressure chamber 10x, diaphragm 20, electromechanical conversion element 30) that discharges the liquid is referred to as a drive channel 3 (drive ch).

Next, the configuration of the liquid discharge head 2 including the wiring and the like will be described. 4A and 4B are views illustrating the wiring and the like of the liquid discharge head 2, FIG. 4A is a cross-sectional view, and FIG. 4B is a plan view. In addition, in FIG. 4B, the illustration of the insulating protective film 40 and 70 is omitted.

In the example of FIG. 4, the insulating protective film 40 is composed of two layers (insulating protective films 40a and 40b). A plurality of wirings 60 are provided on the second layer of the insulating protective film 40b, and an insulating protective film 70 (second insulating protective film) is further provided on the wiring 60. The insulating protective film 40 includes a plurality of openings 40x, and the surface of the lower electrode 31 or the upper electrode 33 is exposed in the openings 40x. The wiring 60 includes a wiring connected to the upper electrode 33 via the opening 40x (the portion of the contact hole H in FIG. 4B) and a wiring connected to the lower electrode 31 via the opening 40x. Includes.

The insulating protective film 70 includes a plurality of openings 70x, and the surface of each wiring 60 is exposed in each opening 70x. The respective wirings 60 exposed in the respective openings 70x are the electrode pads 61, 62, and 63. Here, the electrode pad 61 is a common electrode pad, and is connected to a lower electrode 31 common to each electromechanical conversion element 30 via wiring 60. Further, the electrode pads 62 and 63 are individual electrode pads, and are connected to an independent upper electrode 33 for each electromechanical conversion element 30 via wiring 60.

<Dripping (curving) of the diaphragm>
By the way, in the step of manufacturing the liquid discharge head 2, when the pressure chamber 10x is manufactured, the diaphragm 20 bends (curves) so as to be convex toward the pressure chamber 10x, as shown in FIG. That is, in a state where no voltage is applied to the electromechanical conversion element 30, the diaphragm 20 bends (curves) so as to be convex toward the pressure chamber 10x side. Therefore, the diaphragm 20 is formed in a state of being bent convexly toward the pressure chamber 10x side. The amount of deflection of the diaphragm 20 affects the amount of displacement of the diaphragm 20. Further, when the diaphragm 20 is bent, residual vibration is generated when the ink is discharged. In order to suppress the residual vibration, it is necessary to generate a predetermined waveform, but it is necessary to reduce the frequency of the predetermined waveform, and it becomes difficult to secure the ejection performance at a high frequency.

In order to secure the ejection performance at high frequency, it is necessary to increase the rigidity of the diaphragm 20, the electromechanical conversion film 32, and the insulating protective film 40, and it is necessary to use a material having a high Young's modulus or to make the film thicker. .. In the liquid discharge head 2, the diaphragm 20 is formed from a plurality of layers including silicon oxide film (SiO ₂ ), silicon nitride film (SiN), polysilicon (Poly-Si), etc. in consideration of stress design. be able to. The thickness of the diaphragm 20 is preferably 1 μm or more and 3 μm or less. Further, by setting the Young's modulus of the diaphragm 20 to 75 GPa or more and 95 GPa or less, the ejection performance at a high frequency can be ensured.

Next, the amount of bending of the diaphragm 20 will be described. First, the definition of the amount of deflection of the diaphragm 20 will be described with reference to FIG. In order to calculate the amount of deflection of the diaphragm 20, a deflection amount meter (CCI3000, manufactured by AMETEK, Inc.) is used to acquire the deflection distribution of the diaphragm 20 illustrated in FIG. 6A from the pressure chamber 10x side.

The calculation of the radius of curvature R of the diaphragm 20 based on the acquired deflection distribution will be described. As illustrated in FIG. 5, the central portion of the diaphragm 20 has a large deflection, and both ends have a small deflection. Therefore, in the deflection distribution of the diaphragm 20 illustrated in FIG. 6A obtained by using a deflection amount meter, the points A and B at both ends where the amount of deflection is minimized are used as a reference, and the center becomes the center. Find the point C (center point of deflection). Next, let X be the distance between the points A and B at both ends and the center point C of the deflection. Then, two points D and E at a distance of 0.8X are obtained with reference to the center point C of the deflection. Next, as shown in FIG. 6B, the intersection of the line connecting the points D and E and the perpendicular line to the center point C is defined as the point F, and the distance between the points F and the point C is defined as the distance Y. This distance Y can be obtained from the difference between the height at the points D and E and the height at the center point C in the deflection distribution, and the distance between the points O and F is calculated assuming that the center of the circle of curvature is the point O. can. Therefore, in a right triangle consisting of points O, E, and F, the radius of curvature R can be calculated using the three-square theorem.

In the following description, unless otherwise specified, the radius of curvature R is calculated by the above calculation method, but the method of calculating the radius of curvature R of the diaphragm 20 is limited to the method shown in FIG. For example, in the deflection distribution of the diaphragm 20, the center point of the deflection (the above point C) is obtained, and the point C and the two points separated from the point C on both ends by a predetermined distance are 3 points. It may be calculated based on the coordinate points of the points.

<Material of liquid discharge head, etc.>
Next, suitable materials and the like constituting the liquid discharge head 2 will be described. As the substrate 10, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry, and the liquid discharge head 2 is also mainly (1). A single crystal substrate having a plane orientation of 100) can be used.

Further, when the pressure chamber 10x is produced, the silicon single crystal substrate is processed by using etching. In this case, anisotropic etching is preferably used as the etching method. Anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure.

For example, in anisotropic etching in which the surface is immersed in an alkaline solution such as KOH, the etching rate of the (111) surface is about 1/400 of that of the (100) surface. Therefore, in the plane orientation (100), a structure having an inclination of about 54 ° can be produced, whereas in the plane orientation (110), a deep groove can be dug. Therefore, since the arrangement density can be increased while maintaining the rigidity, the liquid discharge head 2 may also use the single crystal substrate having the plane orientation of (110). However, in this case, it should be noted that SiO ₂ which is a mask material is also etched.

The width (length in the lateral direction) of the pressure chamber 10x is preferably 50 μm or more and 250 μm or less, and more preferably 60 μm or more and 150 μm or less.

The diaphragm 20 is deformed and displaced by receiving a force generated by the electromechanical conversion film 32, and ejects ink droplets in the pressure chamber 10x. Therefore, it is preferable that the diaphragm 20 has a predetermined strength. Specific examples thereof include those produced by Si, SiO ₂ , Si ₃ N ₄ and the like by a CVD method or the like. Further, as the material of the diaphragm 20, it is preferable to select a material having a coefficient close to the linear expansion coefficient of the lower electrode 31 and the electromechanical conversion film 32.

In particular, when PZT is used as the electromechanical conversion membrane 32, the material of the diaphragm 20 is 5 × ^{10-6 (1 / K), which is close to the linear expansion coefficient of PZT of 8 × 10-6 (} 1 / K). It is preferable to select a material having a linear expansion coefficient of about 10 × 10 ^-6 (1 / K). It is more preferable to select a material having a linear expansion coefficient of about 7 × 10 ^-6 (1 / K) to 9 × 10 ^-6 (1 / K).

Specific materials for the vibrating plate 20 include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide and compounds thereof. These can be produced by a spin coater using a sputtering method or a Sol-gel method.

The film thickness of the diaphragm 20 is preferably 1 to 10 μm, more preferably 2 to 5 μm.

As the lower electrode 31 and the upper electrode 33, platinum having high heat resistance and low reactivity can be used as a metal material. However, platinum may not have sufficient barrier properties against lead, in which case platinum group elements such as iridium and platinum-rhodium, or alloy films thereof can be used. ..

When platinum is used as the lower electrode 31 and the upper electrode 33, the adhesion to the underlying diaphragm 20 (particularly SiO ₂ ) is poor, so Ti, TIO ₂ , Ta, Ta ₂ O ₅ , and Ta It is preferable to stack them via an _adhesion layer such as _3N5 . As a method for manufacturing the lower electrode 31 and the upper electrode 33, vacuum film formation such as a sputtering method or vacuum vapor deposition can be used. The film thickness of the lower electrode 31 and the upper electrode 33 is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm.

Further, in the lower electrode 31 and the upper electrode 33, an oxide electrode film made of SrRuO ₃ or LaNiO ₃ may be formed between the metal material and the electromechanical conversion film 32. The oxide electrode film between the lower electrode 31 and the electromechanical conversion film 32 also affects the orientation control of the electromechanical conversion film 32 (for example, PZT film) produced on the oxide electrode film, and therefore the orientation should be prioritized. The material selected depends on the orientation.

In the liquid discharge head 2, when a piezoelectric material such as PZT is used as the electromechanical conversion film 32 and preferentially oriented to PZT (100), a seed layer such as LaNiO ₃ , TiO ₂ , or PbTiO ₃ is used as the lower electrode 31. It is preferable to prepare it on a metal material and then form a PZT film.

Further, an SRO film can be used as the oxide electrode film between the upper electrode 33 and the electromechanical conversion film 32, and the thickness of the SRO film is preferably 20 nm to 80 nm, more preferably 30 nm to 50 nm.

As the electromechanical conversion film 32, lead zirconate titanate (PZT) can be preferably used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics of PZT differ depending on the ratio of PbZrO ₃ and PbTiO ₃ . For example, PZT (Zr0.53, Ti0.47) O3 _, generally PZT (53/47), or the like, which has a ratio of PbZrO ₃ to PbTiO ₃ of 53:47 and is represented by a chemical formula, is used. be able to.

When PZT is used as the electromechanical conversion film 32 and the PZT (100) plane is preferentially oriented, the composition ratio of Zr / Ti is preferably 0.45 or more and 0.55 or less. , 0.48 or more and 0.52 or less is more preferable.

The crystal orientation is represented by ρ (hkl) = I (hkl) / ΣI (hkl). Here, ρ (hkl) is the degree of orientation in the (hkl) plane orientation, I (hkl) is the peak intensity of any orientation, and ΣI (hkl) is the sum of the peak intensities. The degree of orientation of (100) orientation calculated based on the ratio of the peak intensities of each orientation when the sum of the peak intensities obtained by the θ-2θ measurement of the X-ray diffraction method is 1, is 0.75 or more. It is preferably 0.85 or more, and more preferably 0.85 or more.

As a method for producing the electromechanical conversion film 32, it can be produced by a spin coater using a sputtering method or a Sol-gel method. In that case, since patterning is required, a desired pattern can be obtained by photolithography etching or the like.

When PZT is produced by the Sol-gel method, first, lead acetate, zirconium alkoxide, and titanium alkoxide compound are used as starting materials. Then, a PZT precursor solution can be prepared by dissolving it in methoxyethanol, which is a common solvent, to obtain a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by the moisture in the atmosphere, an appropriate amount of acetylacetone, acetic acid, diethanolamine or the like may be added as a stabilizer to the PZT precursor solution.

When a PZT film is formed on the entire surface of the lower electrode 31, it is obtained by forming a coating film by a solution coating method such as spin coating and performing heat treatments of solvent drying, thermal decomposition, and crystallization. Since the transformation from the coating film to the crystallized film is accompanied by volume shrinkage, it is necessary to adjust the concentration of the PZT precursor so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film. ..

The film thickness of the electromechanical conversion film 32 is preferably 1 to 3 μm, more preferably 1.5 to 2.5 μm.

As the electromechanical conversion film 32, an ABO3 type perovskite type crystalline film other than PZT may be used. As the ABO3 type perovskite type crystalline film other than PZT, for example, a lead-free composite oxide film such as barium titanate may be used. In this case, a barium titanate precursor solution can be prepared by using a barium alkoxide or a titanium alkoxide compound as a starting material and dissolving it in a common solvent.

These materials are described by the general formula ABO3, and correspond to a composite oxide containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. As a specific description thereof, it is expressed as (Pb _1-x , Ba) (Zr, Ti) O ₃ , (Pb _1-x , Sr) (Zr, Ti) O ₃ , which is one of Pb of A site. This is the case when the parts are replaced with Ba or Sr. Such substitution is possible if it is a divalent element, and its effect is to reduce the deterioration of characteristics due to evaporation of lead during heat treatment.

As the material of the insulating protective film 40, it is necessary to select a material that prevents damage to the piezoelectric element due to the film forming and etching processes and that makes it difficult for moisture in the atmosphere to permeate. Therefore, it is possible to use a dense inorganic material. preferable.

In order to obtain high protection performance with a thin film, it is preferable to use an oxide, a nitride, or a carbonized film, but a material having high adhesion to an electrode material, a piezoelectric material, and a diaphragm material as a base of the insulating protective film 40 is used. It is necessary to select. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element. That is, the plasma CVD method in which the reactive gas is converted into plasma and deposited on the substrate, or the sputtering method in which the plasma is collided with the target material and blown to form a film is not preferable. As a preferable film forming method, a vapor deposition method, an ALD method (Atomic Layer Deposition) and the like can be exemplified, but the ALD method having a wide choice of materials that can be used is preferable. In particular, by using the ALD method, a thin film having a very high film density can be produced and damage during the process can be suppressed.

As a preferable material for the insulating protective film 40, it is necessary to pay attention to the film stress, and for example, a film material having a tensile stress such as SiN is preferable. In addition, oxide films used for ceramic materials such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ can also be used.

The film thickness of the insulating protective film 40 needs to be a thin film sufficient to secure the protective performance of the electromechanical conversion element 30, and at the same time, it needs to be as thin as possible so as not to hinder the displacement of the diaphragm 20. The film thickness of the insulating protective film 40 is preferably in the range of 20 nm to 100 nm.

Further, a configuration in which the insulating protective film 40 is formed into two layers (insulating protective films 40a and 40b) is also conceivable. In this case, in order to thicken the insulating protective film 40b of the second layer, there is also a configuration in which the insulating protective film 40b of the second layer is opened in the upper electrode 33 so as not to significantly hinder the vibration displacement of the diaphragm 20. .. For example, in the case of using the drive channel 3 or the dummy channel 4 to have two layers of the insulating protective film 40, the thickened second layer of the insulating protective film 40b may be opened.

At this time, as the insulating protective film 40b of the second layer, any oxide, nitride, carbide or a composite compound thereof can be used, but SiO ₂ generally used in semiconductor devices can be used. Any method can be used for film formation, and a CVD method and a sputtering method can be exemplified, and it is preferable to use a CVD method capable of forming an isotropic film in consideration of the step coating of the pattern forming portion such as the electrode forming portion. The film thickness of the second layer of the insulating protective film 40b needs to be a film thickness that does not cause dielectric breakdown due to the voltage applied to the lower electrode 31 and the wiring 60. That is, it is necessary to set the electric field strength applied to the insulating protective film within a range that does not cause dielectric breakdown. Further, the film thickness is required to be 200 nm or more, more preferably 500 nm or more, in consideration of the surface property of the base of the second layer of the insulating protective film, pinholes and the like.

The function of the insulating protective film 70 is a passivation layer having the function of a protective layer of the wiring 60. As shown in FIG. 4, the upper electrode 33 and the lower electrode 31 are covered except for the positions of the electrode pads 61 and 62 (opening 70x). As a result, an inexpensive Al or an alloy material containing Al as a main component can be used as the electrode material. As a result, the liquid discharge head 2 can be obtained at low cost and with high reliability.

As the material of the insulating protective film 70, it is necessary to pay attention to the film stress as well as the insulating protective film 40, and for example, a film material having a tensile stress such as SiN is preferable.

Further, as the material of the insulating protective film 70, any inorganic material or organic material can be used, but it is necessary to use a material having low moisture permeability. Examples of the inorganic material include oxides, nitrides and carbides, and examples of the organic material include polyimide, acrylic resin and urethane resin. However, in the case of an organic material, it is not suitable because a thick film is required. Therefore, it is preferable to use an inorganic material that can exhibit a wiring protection function with a thin film. In particular, it is preferable to use Si ₃ N ₄ on the Al wiring because it is a technique with a proven track record in semiconductor devices.

The film thickness is preferably 200 nm or more, more preferably 500 nm or more.

Further, a structure having an opening on the electromechanical conversion element 30 and the diaphragm 20 around the electromechanical conversion element 30 is preferable. This is the same reason as the thinning of the individual liquid chamber region of the insulating protective film 40. This makes it possible to obtain a highly efficient and highly reliable liquid discharge head 2.

The material of the wiring 60 is preferably a metal electrode material made of any one of Ag alloy, Cu, Al, Au, Pt, and Ir. As a manufacturing method, it is manufactured by a sputtering method or a spin coating method, and then a desired pattern is obtained by photolithography etching or the like. The film thickness is preferably 0.1 to 20 μm, more preferably 0.2 to 10 μm.

The contact resistance in the contact hole portion (for example, 10 μm × 10 μm) is preferably 10 Ω or less for the lower electrode 31, 1 Ω or less for the upper electrode 33, and more preferably 5 Ω or less for the lower electrode 31 and the upper electrode. As 33, it is 0.5Ω or less.

<Liquid discharge head with groove>
It is known that the liquid discharge head 2 is provided with a groove on the end side of the pressure chamber 10x in the arrangement direction in order to prevent the adhesive from flowing into the liquid flow path when the substrates are joined to each other as described above. In the groove, it is possible to introduce an excess adhesive for joining the pressure chamber forming substrate to another substrate.

Regarding the variation in the displacement amount of the drive channel 3 on the end side, it was found that a means for suppressing the variation corresponding to the case of providing the groove is required.

FIG. 7 is a cross-sectional view illustrating the liquid discharge head 2 provided with the groove 11. The liquid discharge head 2 shown in FIG. 7 is provided with a groove 11 formed by etching the substrate 10 from the direction in which the nozzle 51 is formed, similar to the pressure chamber 10x, on the end side of the pressure chamber 10x in the arrangement direction. ing. The groove 11 is a through groove penetrating the substrate 10 in the thickness direction, and the pressure chamber 10x and the diaphragm 20 on the groove 11 are exposed. In the example of FIG. 7, four grooves 11 are formed on one end side of the pressure chamber 10x in the arrangement direction, but the number of grooves 11 formed is only one example and is limited to this. is not it. Further, in the example of FIG. 7, one end side of the pressure chamber 10x on the one end side in the arrangement direction is shown, but the other end side also has the same configuration, and the groove 11 is formed.

At the position where the groove 11 is formed, the diaphragm 20 forms a part of the wall surface of the groove 11, the electromechanical conversion element 30 is not formed on the diaphragm 20, and the insulating protective film 40 is formed on the diaphragm 20. The wiring 60 and the insulating protective film 70 are formed in this order. The wiring 60 is a wiring layer that supplies a drive signal and drive power to the electromechanical conversion element 30.

After that, the nozzle plate 50 having the nozzle 51 on the lower surface of the substrate 10 is joined by the adhesive 80. FIG. 8 shows an example in which the nozzle plate 50 is joined to the liquid discharge head 2 shown in FIG. 7. As shown in FIG. 8, the nozzle 51 is formed at a position corresponding to the pressure chamber 10x, and is not formed at a position corresponding to the groove 11.

As shown in FIG. 7, the inventors of the present application examined the degree of bending (the way of bending and the amount of bending) of the diaphragm 20 with respect to the liquid discharge head 2 having the groove 11 formed. It was found that the deflection of the diaphragm 20 on the groove 11 affects the deflection of the diaphragm 20 at the formation position of the electromechanical conversion element 30 on both ends near the groove 11.

FIG. 9 is a cross-sectional view illustrating the liquid discharge head 2 which does not form the groove 11 in the liquid discharge head 2 having the same configuration as that of FIG. 7. For comparative study, as shown in FIG. 9, the degree of bending of the diaphragm 20 was examined for the liquid discharge head 2 having the same configuration as that of FIG. 7 except that the groove 11 was not formed.

10 shows the amount of deflection of the diaphragm 20 in channels 1 to 20 from the end of the drive channel 3 in the configuration having the groove 11 shown in FIG. 7 and the configuration without the groove 11 shown in FIG. , The amount of deflection of the diaphragm 20 at 40 channels and 80 channels from the end is shown.

According to FIG. 10, in the configuration shown in FIG. 7, the amount of bending in the drive channel 3 on the end side is small, and the degree of bending of the diaphragm 20 of the drive channel 3 on the end side and the drive channel 3 on the center side is On the other hand, in the configuration shown in FIG. 9, even if the membrane configuration on the diaphragm 20 is different, it is not affected by the difference, and the drive channel 3 on the end side near the groove 11 is not affected. It can be seen that there is no difference between the degree of bending of the diaphragm 20 and the degree of bending of the diaphragm 20 of the drive channel 3 on the central side away from the groove 11.

As a result of this examination, there is a difference between the degree of bending of the diaphragm 20 of the drive channel 3 on the end side near the groove 11 and the degree of bending of the diaphragm 20 of the drive channel 3 on the central side away from the groove 11. It was found that the presence or absence of the formation of the groove 11 affects the degree of bending of the diaphragm 20 between the drive channels. It is considered that this is because the degree of bending of the diaphragm 20 of the drive channel 3 on the end side near the groove 11 changes due to the stress effect from the diaphragm 20 at the formation position of the groove 11. As described above, if the degree of bending of the diaphragm 20 varies among the drive channels of the liquid discharge head 2, the discharge performance is affected.

On the other hand, regarding the formation position of the groove 11, if the layer structure on the diaphragm 20 can be made the same as the layer structure of the diaphragm 20 of the drive channel 3, the diaphragm 20 at the formation position of the groove 11 can be used. It is also considered that the stress effect of the above can be reduced and the variation of the deflection between the drive channels can be suppressed.

However, in consideration of wiring resistance and the like, it is difficult to align all of the arrangement directions in the liquid discharge head 2 with exactly the same structure as the drive channel 3, and as shown in FIG. 7, the drive channel 3 on the end side is used. In order to reduce the wiring resistance, it is necessary to form the wiring 60 on the outer structure without forming the electric-mechanical conversion film 32.

In the liquid discharge head (liquid discharge head 2) according to the present embodiment, the pressure chambers (pressure chambers 10x) for liquid discharge communicating with a plurality of nozzles (nozzles 51) for discharging liquids are arranged in a predetermined direction (pressure chambers 10x). A pressure chamber forming substrate formed side by side in the direction) and a vibrating plate layer (vibration plate 20) provided on the side opposite to the nozzle side of the pressure chamber forming substrate, and a part of which constitutes the wall surface of the pressure chamber. And an electromechanical conversion element (electromechanical conversion element 30) provided on the vibrating plate layer corresponding to each pressure chamber, and the pressure chamber forming substrate is provided on the end side of the pressure chamber in a predetermined direction. A groove (groove 11) having an open surface on the nozzle side is formed, the vibrating plate layer on the pressure chamber is formed by bending toward the pressure chamber side, and the vibrating plate layer on the groove is formed on the opening side of the groove. It is formed by bending. The numbers in parentheses indicate the reference numerals and application examples in the embodiment.

That is, the bending directions of the diaphragm 20 on the groove 11 and the diaphragm 20 of the drive channel 3 are the same. Here, it is preferable that the degree of bending of the diaphragm 20 of the drive channel 3 is larger than that of the diaphragm 20 on the groove 11. The radius of curvature R of the diaphragm 20 at the position where the groove 11 is formed is preferably 2000 μm or more, more preferably 6000 μm or more.

Here, as shown in FIG. 5, the diaphragm 20 at the drive channel 3 position is convex toward the pressure chamber 10x when the pressure chamber 10x is created in the step of manufacturing the liquid discharge head 2. It bends so that it becomes. That is, the diaphragm 20 on the pressure chamber 10x is formed so as to be convexly bent (curved) toward the pressure chamber 10x for each pressure chamber 10x.

On the other hand, as described above, the insulating protective film 40, the wiring 60, and the insulating protective film 70 are formed on the diaphragm 20 on the groove 11, and the electromechanical conversion element 30 is not formed. This is because it is necessary to reduce the wiring resistance, and it is preferable to increase the region forming the wiring 60 in the region other than the drive channel 3.

That is, since the electromechanical conversion element 30 having a strong tensile stress is not formed on the diaphragm 20 on the groove 11, the diaphragm 20 on the groove 11 has a film stress state different from that of the diaphragm 20 of the drive channel 3. It will be different.

That is, the diaphragm 20 of the drive channel 3 is flexed so as to be convex toward the pressure chamber 10x due to the tensile stress, whereas the diaphragm 20 on the groove 11 is subjected to the compressive stress to the groove 11. Will bend so that it becomes convex on the opposite side.

In this way, when the stress state of the deflection of the diaphragm 20 on the groove 11 (compressive stress) and the stress state of the deflection of the diaphragm 20 of the drive channel 3 (tensile stress) are different, the end side of the drive channel 3 The amount of bending at (for example, 20 channels from the end) becomes large, and the amount of displacement varies, which affects the bending of the diaphragm 20.

Therefore, in the present embodiment, the groove 11 is controlled by controlling the layer structure on the diaphragm 20 on the groove 11, that is, the thickness and material of the wiring 60, and / or the thickness and material of the insulating protective films 40 and 70. The bending direction and the degree of bending of the upper diaphragm 20 are adjusted so that the bending of the diaphragm 20 on the groove 11 is bent so as to be convex toward the groove 11 for each groove 11, so that the diaphragm 20 of the drive channel 3 is bent. It is the same as the bending direction. In other words, the stress state is such that tensile stress also acts on the diaphragm 20 on the groove 11.

Further, it is preferable that the degree of bending at that time is sufficiently small so that it is smaller than the degree of bending of the diaphragm 20 of the drive channel 3.

For example, as described above, it is preferable to use SiN films having tensile stress for the insulating protective films 40 and 70. At this time, by controlling the film thickness of the SiN film, it is possible to adjust the stress state to the same as that of the diaphragm 20 of the drive channel 3. If the tensile stress on the groove 11 is too large, the amount of deflection on the end side (for example, 20 channels from the end) of the drive channel 3 will be large, and variation will occur. The tensile stress on the groove 11 needs to be adjusted appropriately.

By controlling the layer configuration on the diaphragm 20 on the groove 11 in this way, the bending direction of the diaphragm 20 on the groove 11 and the diaphragm 20 of the drive channel 3 is set to the same side, and the bending direction on the groove 11 is set to the same side. The degree of bending of the diaphragm 20 of the drive channel 3 can be made larger than that of the diaphragm 20.

As described above, the liquid discharge head 2 according to the present embodiment has a small influence on the diaphragm 20 of the drive channel 3 even if it is affected by the bending of the diaphragm 20 on the groove 11. As a result, even in the configuration having the groove 11, the amount of deflection of the diaphragm 20 between the drive channels is suppressed so as to suppress the influence of the drive channel 3 on the end side close to the groove 11 on the deflection of the diaphragm 20. It is possible to suppress the occurrence of variation.

Next, a method for evaluating the degree of bending will be described. The degree of bending can be evaluated by using, for example, the radius of curvature R of the diaphragm 20. The radius of curvature R may be calculated by, for example, the calculation method described with reference to FIG.

11A is an explanatory diagram showing the radius of curvature of the diaphragm 20 at the position where the groove 11 is formed, and FIG. 11B is an explanatory diagram showing the radius of curvature of the diaphragm 20 of the drive channel 3. The illustration of the layer structure on the diaphragm 20 is omitted. When the radius of curvature of the diaphragm 20 at the formation position of the groove 11 is Ra and the radius of curvature of the diaphragm 20 of the drive channel 3 is Rb, it is preferable to satisfy Ra> Rb.

Further, the degree of bending can be evaluated by using the amount of bending of the diaphragm 20. FIG. 12A is an explanatory diagram showing the amount of deflection of the diaphragm 20 at the position where the groove 11 is formed, and FIG. 12B is an explanatory diagram showing the amount of deflection of the diaphragm 20 of the drive channel 3.

Here, as shown in FIG. 12, a line showing the formation position of the diaphragm 20 in the deflection distribution of the diaphragm 20 from the center point C of the deflection assuming that the diaphragm 20 has no deflection (FIG. 12). The length of the vertical line to the dotted line inside) is defined as the amount of deflection. Then, when the amount of bending of the diaphragm 20 at the formation position of the groove 11 and the amount of bending of the diaphragm 20 of the drive channel 3 are b, it is preferable to satisfy a <b.

Up to this point, an example of defining the relationship between the diaphragm 20 at the formation position of the groove 11 and the degree of deflection of the diaphragm 20 of the drive channel 3 has been described, but the relationship with the amount of deflection of the diaphragm 20 of the drive channel 3 is not necessarily described. Is not required to be specified, and by setting the bending direction of the diaphragm 20 at the formation position of the groove 11 to the groove 11 side and setting the radius of curvature to a sufficiently large value, the diaphragm 20 of the drive channel 3 group is set. It is possible to suppress the occurrence of variation in the amount of deflection.

Next, the size of the groove 11 and the formation position will be described. FIG. 13A is a cross-sectional view in the arrangement direction of the pressure chambers of the liquid discharge head 1 in a state where the nozzle plate 50 is not joined, and FIG. 13B is a plan view seen from the nozzle plate 50 side. The example shown in FIG. 13 has the same layer structure as the liquid discharge head 2 shown in FIG. 7, but the spacing between the grooves 11 and the drive channel 3 at the end (pressure chamber 10x at the end) and the groove 11 are the same. The distance to and from is set to satisfy a predetermined relationship.

Here, as shown in FIG. 13, the arrangement direction of the pressure chambers 10x (the short side direction of the pressure chambers) is the X direction, and the direction orthogonal to the arrangement direction (the longitudinal direction of the pressure chambers) is the Y direction. When the size of the groove 11 in the X direction is X1, the size in the Y direction is Y1, the size of the pressure chamber 10x in the X direction is X2, and the size in the Y direction is Y2, the following equation (1) is satisfied. It is preferable to have.
X1 ≤ X2 and Y1 <Y2 ... (1)

As described above, by making the size of the groove 11 smaller than that of the pressure chamber 10x, the stress effect can be more preferably reduced. The size in the X direction may be the same (X1 = X2).

The size of the groove 11 is preferably 100 μm or less for both X1 and Y1, and more preferably 50 μm.

The arrangement interval of the grooves 11 is preferably 30 μm or more in the X direction, 30 μm or more in the Y direction, and more preferably 100 μm or more.

The distance Z between the drive channel 3 at the end (the pressure chamber 10x at the end) and the groove 11 is preferably 100 μm or more, more preferably 200 μm.

By forming the groove 11 so as to satisfy a predetermined condition in this way, it is possible to more preferably reduce the stress effect on the drive channel 3 at the end and suppress the performance variation between the drive channels. Can be done.

According to the liquid discharge head 2 according to the present embodiment described above, in the configuration having the groove 11, it is possible to suppress the occurrence of variation in the degree of bending of the diaphragm 20 between the drive channels and obtain good discharge performance. ..

The present invention is not limited to the configuration of the liquid discharge head 2 shown in FIGS. 7 and 13, and various other liquid discharges having a configuration corresponding to the groove 11 such as a relief groove for introducing excess adhesive. It can be applied to the head.

[Second Embodiment]
Hereinafter, other embodiments of the liquid discharge head according to the present invention will be described. The description of the same points as in the above embodiment will be omitted as appropriate.

In the liquid discharge head 2, for example, as shown in FIG. 14, a dummy having a dummy electromechanical conversion element 34 that does not discharge droplets is provided on the end side of the electromechanical conversion element 30 (drive channel 3) in the arrangement direction. It is known that by disposing the channel 4, air bubbles at the time of filling the liquid are discharged and the filling property of the liquid is improved (Reference: Japanese Patent Application Laid-Open No. 2014-177049). In the liquid discharge head 2, the dummy pressure chamber 12 (FIG. 15), the diaphragm 20, and the electromechanical conversion element 30 that are not intended to discharge liquid are referred to as dummy channels 4 (dummy channels).

Therefore, in the second embodiment, in the arrangement direction of the pressure chamber 10x, the dummy channel 4 is provided on the end side of the drive channel 3, and the groove 11 is further provided on the end side of the dummy channel 4. .. The number of arrays (number of channels) of the dummy channels 4 may be 1 or more per end portion, but it is preferable that 3 or more are arranged per end portion in order to improve the filling property of the liquid.

FIG. 15 is a diagram showing another embodiment (second embodiment) of the liquid discharge head 2. FIG. 15A is a cross-sectional view in the arrangement direction of the pressure chambers of the liquid discharge head 1 in a state where the nozzle plate 50 is not joined, and FIG. 15B is a plan view seen from the nozzle plate 50 side. Further, FIG. 16 shows an example in which the nozzle plate 50 is joined to the liquid discharge head 2 shown in FIG. 15 with an adhesive 80. As shown in FIG. 16, the nozzle 51 is formed at a position corresponding to the pressure chamber 10x, and is not formed at a position corresponding to the dummy pressure chamber 12 and the groove 11.

Here, the configuration of the pressure chamber (dummy pressure chamber 12) of the dummy channel 4 and the layer configuration on the diaphragm 20 of the dummy channel 4 may be the same configuration as that of the drive channel 3. Therefore, the diaphragm 20 of the dummy channel 4 also bends so that the diaphragm 20 is convex toward the dummy pressure chamber 12 when the dummy pressure chamber 12 is manufactured in the step of manufacturing the liquid discharge head 2. Therefore, the diaphragm 20 is formed in a state of being convexly bent toward the dummy pressure chamber 12 for each dummy pressure chamber 12.

Further, the distance Z between the endmost dummy channel 4 (the endmost dummy pressure chamber 12) and the groove 11 is preferably 30 μm or more, more preferably 100 μm. The size of the grooves 11, the spacing between the grooves 11 and the like are preferably the same as those in the first embodiment.

In the second embodiment, the bending directions of the diaphragm 20 on the groove 11, the diaphragm 20 of the dummy channel 4, and the diaphragm 20 of the drive channel 3 are all the same. Further, it is preferable that the degree of bending of the diaphragm 20 of the dummy channel 4 and the drive channel 3 is larger than that of the diaphragm 20 on the groove 11.

By making the bending directions of the diaphragm 20 on the groove 11, the diaphragm 20 of the dummy channel 4, and the diaphragm 20 of the drive channel 3 all the same, it is possible to suppress the influence of stress from the groove 11 side.

Further, by making the degree of bending of the diaphragm 20 of the dummy channel 4 and the drive channel 3 larger than that of the diaphragm 20 on the groove 11, the influence of stress from the groove 11 side can be suppressed.

According to the liquid discharge head according to the second embodiment described above, the influence of stress on the drive channel 3 at the end portion from the groove 11 side can be reduced, and the performance variation between the drive channels can be suppressed. Further, by providing the dummy channel 4 between the drive channel 3 and the groove 11 in the arrangement direction of the pressure chamber 10x, the liquid is filled as compared with the configuration without the dummy channel 4 (first embodiment). The sex can be good.

[Third Embodiment]
FIG. 17 is a diagram showing another embodiment (third embodiment) of the liquid discharge head 2. FIG. 17A is a cross-sectional view in the arrangement direction of the pressure chambers of the liquid discharge head 1 in a state where the nozzle plate 50 is not joined, and FIG. 17B is a plan view seen from the nozzle plate 50 side.

In the first and second embodiments, the groove 11 is configured to penetrate the substrate 10, but in the third embodiment, the groove 11 is opened on the surface of the substrate 10 on the nozzle 51 side, and the substrate is opened. It has a non-penetrating shape that does not penetrate 10.

In the liquid discharge head according to the third embodiment described above, a part of the substrate 10 exists between the diaphragm 20 and the groove 11. Therefore, by preventing the diaphragm 20 on the groove 11 from bending, the stress effect on the drive channel 3 at the end portion from the groove 11 side can be reduced, and the performance variation between the drive channels can be suppressed. Can be done.

[Fourth Embodiment]
FIG. 18 is a cross-sectional view showing another embodiment (fourth embodiment) of the liquid discharge head 2. Up to this point, an example in which the nozzle plate 50 is directly bonded to the substrate 10 has been described, but the substrate bonded to the nozzle 51 side of the substrate 10 is not limited to the nozzle plate 50. For example, as shown in FIG. 18, a communication pipe substrate 90, which is a substrate provided with a communication pipe for communicating the pressure chamber 10x and the nozzle 51, is joined to the substrate 10, and the communication pipe substrate 90 is joined to the nozzle plate 50. It may be a thing.

(Device for discharging liquid)
An example of a device for discharging a liquid having a liquid discharge head according to the present invention will be described with reference to FIGS. 19 and 20. FIG. 19 is an explanatory plan view of a main part of the device, and FIG. 20 is an explanatory view of a side surface of the main part of the device.

This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which a liquid discharge head 2 and a head tank 441 are integrated. The liquid discharge head 2 of the liquid discharge unit 440 discharges, for example, liquids of each color of yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 2 has a nozzle row composed of a plurality of nozzles 51 arranged in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the discharge direction facing downward.

The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 2 to the liquid discharge head 2.

The supply mechanism 494 includes a cartridge holder 451 which is a filling part for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is delivered from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

This device includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head 2. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head 2 is arranged on the side of the transport belt 412.

The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle 51 is formed) of the liquid discharge head 2, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In this apparatus configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyor belt 412.

Therefore, by driving the liquid ejection head 2 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is ejected onto the stopped paper 410 to form an image.

As described above, since this device is provided with the above-mentioned liquid discharge head, there is no liquid discharge failure due to a diaphragm drive failure, stable liquid discharge characteristics are obtained, and a high-quality image is stably formed. can do.

(Liquid discharge unit)
Next, an example of a liquid discharge unit having a liquid discharge head according to the present invention will be described with reference to FIG. 21. FIG. 21 is an explanatory plan view of a main part of the unit.

This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning moving mechanism 493, a carriage 403, and a liquid discharge among the members constituting the device for discharging the liquid. It is composed of a head 2.

It should be noted that a liquid discharge unit may be configured in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.

Next, another example of the liquid discharge unit having the liquid discharge head according to the present invention will be described with reference to FIG. 22. FIG. 22 is a front explanatory view of the unit.

This liquid discharge unit is composed of a liquid discharge head 2 to which the flow path component 444 is attached and a tube 456 connected to the flow path component 444.

The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 that electrically connects to the liquid discharge head 2 is provided on the upper part of the flow path component 444.

In the present application, the "device for discharging a liquid" is a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or into the liquid.

The "device for discharging the liquid" may include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming device that is a device that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included. The above-mentioned "material to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as one that adheres and adheres, and one that adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recorded media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, and includes everything to which the liquid adheres, unless otherwise specified.

The material of the above-mentioned "material to which liquid can adhere" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or the like as long as the liquid can adhere even temporarily.

The "liquid" also includes inks, treatment liquids, DNA samples, resists, pattern materials, binders, modeling liquids, or solutions and dispersions containing amino acids, proteins, and calcium.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials. There is an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid dispersed in a solution through a nozzle.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and is a collection of parts related to liquid discharge. For example, the "liquid discharge unit" includes a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, a main scanning movement mechanism in which at least one of the configurations is combined with a liquid discharge head, and the like.

Here, the term "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, bonding, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

For example, as a liquid discharge unit, there is a liquid discharge head and a head tank integrated, such as the liquid discharge unit 440 shown in FIG. In some cases, the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a unit in which a liquid discharge head and a carriage are integrated.

Further, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member constituting a part of the scanning movement mechanism. Further, as shown in FIG. 21, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, as shown in FIG. 22, a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. ..

The main scanning movement mechanism shall include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

Further, the pressure generating means used for the "liquid discharge head" is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described in the above embodiment, it is composed of a thermal actuator using an electric heat conversion element such as a heat generating resistor, a vibrating plate, and a counter electrode. An electrostatic actuator or the like may be used.

Further, in the terms of the present application, image formation, recording, printing, printing, printing, modeling, etc. are all synonymous.

Although the above-described embodiment is a preferred example of the present invention, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

For example, in the above embodiment, the case where the upper electrode is an individual electrode and the lower electrode is a common electrode has been described, but the present invention is not limited to this. That is, the same effect can be obtained even in a configuration in which the upper electrode is a common electrode and the lower electrode is an individual electrode.

Hereinafter, examples of the present invention will be described.

[Example 1]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (film thickness 600 nm), Si (film thickness 200 nm), SiO ₂ (film thickness 100 nm), SiN (film thickness 150 nm), SiO ₂ (film thickness) are prepared on the substrate 10. A vibrating plate 20 was produced by forming films of (130 nm), SiN (thickness 150 nm), SiO ₂ (thickness 100 nm), Si (thickness 200 nm), and SiO ₂ (thickness 600 nm) in this order.

Then, a titanium film (thickness 20 nm) was formed on the diaphragm 20 as an adhesion layer by a sputtering apparatus at a film forming temperature of 350 ° C., and then thermally oxidized at 750 ° C. using RTA (rapid heat treatment). Further, a platinum film (thickness 160 nm) was formed on the adhesion layer by a sputtering apparatus at a film formation temperature of 400 ° C. to prepare a lower electrode 31.

Next, a solution adjusted to Pb: Ti = 1: 1 as a PbTiO ₃ layer to be a base layer on the lower electrode 31 and Pb: Zr: Ti = 115: 49: 51 as an electromechanical conversion film 32 are adjusted. The solution was prepared and a film was formed by the spin coating method.

For the synthesis of a specific precursor coating solution, lead acetate trihydrate, isopropoxide titanium, and isopropoxide zirconium were used as starting materials. The water of crystallization of lead acetate was dissolved in methoxyethanol and then dehydrated. The amount of lead is excessive for the composition of both chemistry. This is to prevent a decrease in crystallinity due to so-called lead loss during heat treatment.

A PZT precursor solution was synthesized by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with an alcohol exchange reaction and an esterification reaction, and mixing with the above-mentioned lead acetate-dissolved methoxyethanol solution. The PZT concentration was 0.5 mol / liter. The PT solution was also prepared in the same manner as PZT, and the PT layer was first formed by spin coating using these solutions, and then dried at 120 ° C., and then the PZT solution was formed by spin coating. The film was formed, dried at 120 ° C., and thermally decomposed at 400 ° C.

After the thermal decomposition treatment of the third layer, a crystallization heat treatment (temperature 730 ° C.) was performed by RTA. At this time, the film thickness of PZT was 240 nm. This step was carried out a total of 8 times (24 layers) to obtain a PZT film of about 2 μm as the electromechanical conversion film 32.

Next, an SrRuO ₃ film (thickness 40 nm) was formed as an oxide electrode film constituting the upper electrode 33, and a platinum film (thickness 125 nm) was formed as a metal film by a sputtering method. After that, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by a spin coating method, a resist pattern was formed by ordinary photolithography, and then a pattern as shown in FIG. 4 was formed using an ICP etching apparatus (manufactured by SAMCO). Made. As a result, the electromechanical conversion element 30 was produced on the diaphragm 20.

Next, an _Al2O3 film was formed on the electromechanical conversion element ₃₀ as an insulating protective film 40a by using the ALD method to form a 50 nm film. At this time, as raw materials, TMA (Sigma-Aldrich) was alternately laminated for Al _, and O3 generated by an ozone generator for O was alternately laminated to proceed with film formation.

Next, as the insulating protective film 40b, Si ₃ N ₄ was formed into a film of 1000 nm by a plasma CVD method, and then, as shown in FIG. 4, a contact hole H was formed by etching. Then, Al was formed into a film by a sputtering method, patterned by etching to form a wiring 60, and Si _{3N 4 was} formed into a film of 500 nm as an insulating protective film 70 by a plasma CVD method.

Then, as shown in FIG. 15, the back surface of the substrate 10 was etched to form a pressure chamber 10x (X2: width 60 μm, Y2: length 1000 μm) to form a liquid discharge head 2. However, the nozzle plate 50 provided with the nozzle 51 is not joined to the lower portion of the substrate 10, and the liquid discharge head 2 is in a semi-finished state.

At this time, as shown in FIG. 23, in order to hold the pressure chamber 10x, a holding substrate 15 having a number of recesses 15x corresponding to the electromechanical conversion element 30 formed on the back surface was used. Specifically, before forming the pressure chamber 10x, the holding substrate 15 was bonded onto the substrate 10 via an adhesive layer so that each electromechanical conversion element 30 was accommodated in each recess 15x. Then, the back surface of the substrate 10 was etched to form a pressure chamber 10x.

At this time, one dummy channel 4 (the number formed on one end side; the same applies hereinafter) was formed, and a groove 11 (X1: width 60 μm, Y1: length 60 μm) was formed. The distance between the adjacent grooves 11 was set to 60 μm in both the X direction and the Y direction. Further, the distance Z between the groove 11 and the dummy channel 4 was set to 60 μm. The radius of curvature of the groove 11 was 2300 μm, and the radius of curvature of the drive channel 3 at the end was 4500 μm.

[Example 2]
Examples except that Si _{3 N 4 was deposited at 700 nm as the insulating protective film 40b by the plasma CVD method, Si 3 N 4 was deposited} at 300 nm as the insulating protective film 70 by the plasma CVD method, and four dummy channels 4 were formed. The liquid discharge head 2 was manufactured in the same manner as in 1. The radius of curvature of the groove 11 was 6400 μm, and the radius of curvature of the drive channel 3 at the end was 4200 μm.

[Example 3]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (film thickness 1200 nm), Si (film thickness 400 nm), SiO ₂ (film thickness 200 nm), SiN (film thickness 300 nm), SiO ₂ (film thickness) are prepared on the substrate 10. A vibrating plate 20 was produced by forming a film of 260 nm), SiN (300 nm), SiO ₂ (film thickness 200 nm), Si (400 nm), and SiO ₂ (film thickness 1200 nm) in this order.

Si ₃ N ₄ is deposited at 700 nm as the insulating protective film 40b by the plasma CVD method, Si ₃ N ₄ is deposited at 300 nm as the insulating protective film 70 by the plasma CVD method, the width of the pressure chamber 10x is 100 μm, and the dummy channel 4 is formed. And formed a groove 11 (X1: width 100 μm, Y1: length 100 μm). The distance between the adjacent grooves 11 was set to 30 μm in both the X direction and the Y direction. The distance between the groove 11 and the dummy channel 4 was set to 30 μm. Except for the above, the liquid discharge head 2 was produced in the same manner as in Example 1. The radius of curvature of the groove 11 was 6200 μm, and the radius of curvature of the drive channel 3 at the end was 4250 μm.

[Example 4]
As shown in FIG. 7, the back surface of the substrate 10 is etched to form a pressure chamber 10x (dummy channel non-formation), Si ₃ N ₄ is formed as an insulating protective film 40b by a plasma CVD method at 700 nm, and the insulating protective film 70 is formed. As a result, Si ₃ N ₄ was formed into a film of 300 nm by a plasma CVD method, and a liquid discharge head 2 was produced in the same manner as in Example 1 except that the distance between the drive channel 3 at the end end and the groove 11 was 100 μm. The radius of curvature of the groove 11 was 6500 μm, and the radius of curvature of the drive channel 3 at the end was 4300 μm.

[Example 5]
As shown in FIG. 17, the back surface of the substrate 10 is etched to form a pressure chamber 10x and four dummy channels 4, and the groove 11 portion is the same as in Example 1 except that the substrate 10 is not penetrated by half etching. The liquid discharge head 2 was manufactured. The radius of curvature of the drive channel 3 at the end was 4400 μm.

[Comparative Example 1]
Si ₃ N ₄ was deposited at 1500 nm as the insulating protective film 40b by the plasma CVD method, Si ₃ N ₄ was deposited at 1000 nm as the insulating protective film 70 by the plasma CVD method, and the back surface of the substrate 10 was etched to form a pressure chamber 10x. The liquid discharge head 2 was produced in the same manner as in Example 1 except that four dummy channels 4 were produced. The radius of curvature of the groove 11 was 1200 μm, and the radius of curvature of the drive channel 3 at the end was 4600 μm.

[Comparative Example 2]
As shown in FIG. 9, the back surface of the substrate 10 was etched to form a pressure chamber 10x, and the liquid discharge head 2 was produced in the same manner as in Example 1 except that the groove 11 and the dummy channel 4 were not formed. The radius of curvature of the drive channel 3 at the end was 4350 μm.

[Examination of Examples 1 to 5 and Comparative Examples 1 and 2]
The liquid discharge heads 2 produced in Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated for nozzle bondability and liquid filling property. Table 1 shows the evaluation results and the details of each example and comparative example.

In Table 1, in Examples 1 to 5, the difference between the maximum value and the minimum value (radius of curvature difference) of the radius of curvature R of the diaphragm 20 in the drive channel group from each end to 20 ch is 1500 μm or less. In Comparative Example 1, it is larger than 2000 μm. Further, in Comparative Example 1, the radius of curvature of the groove 11 is smaller than the radius of curvature of the drive channel 3.

As can be seen from Table 1, in Examples 1 to 5, the displacement difference (Δδ / δ_ave) is within the target 8% as the displacement slope in the channel group from each end in the chip to 20 ch. However, Comparative Example 1 had a large variation of 13%. Note that δ is the displacement characteristic of the electromechanical conversion film 32 when evaluated over an electric field strength of 150 kv / cm, Δδ is the inclination difference of the displacement characteristic δ with respect to the arrangement direction of the electromechanical conversion film 32, and δ_ave is the displacement. It is the average value of the characteristic δ.

A nozzle plate 50 provided with a nozzle 51 is joined to the lower part of the substrate 10 of each liquid discharge head 2 (liquid discharge head 2 in a semi-finished state) manufactured in Examples 1 to 5 and Comparative Examples 1 to 2, and the liquid discharge head is joined. 2 was completed and the liquid discharge was evaluated.

Specifically, using an ink whose viscosity was adjusted to 5 cp, the ejection state when an applied voltage of -10 to -30 V was applied by a simple Push waveform was confirmed. As a result, in Comparative Example 2 in which the groove 11 was not formed, it was confirmed that the adhesive entered the pressure chamber 10x at the time of nozzle bonding (nozzle bonding property: ×).

On the other hand, good nozzle bondability was obtained for each of the liquid discharge heads 2 produced in Examples 1 to 5 in which the groove 11 was formed (nozzle bondability: ⊚). Further, it was confirmed that in Examples 1 to 3 and 5, by providing the dummy channel 4, the filling property of the liquid was improved and the ejection problem due to air bubbles or the like could be solved. Further, in Examples 2 and 3 in which the radius of curvature of the groove 11 is larger than the radius of curvature of the drive channel 3, the filling property is better than that of Example 1 in which the radius of curvature of the groove 11 is smaller than the radius of curvature of the drive channel 3. Was obtained (fillability: ◎).

1, 2 Liquid discharge head 3 Drive channel 4 Dummy channel 10 Board 10 x Pressure chamber 11 Groove 12 Dummy pressure chamber 15 Holding board 15 x Recess 20 Vibrating plate 30 Electromechanical conversion element 31 Lower electrode 32 Electromechanical conversion film 33 Upper electrode 34 Dummy electricity Mechanical conversion element 40 (40a, 40b), 70 Insulation protective film 40x, 70x Opening 50 Nozzle plate 51 Nozzle 60 Wiring 61,62,63 Electrode pad 80 Adhesive 90 Communication tube substrate

Japanese Unexamined Patent Publication No. 2007-32171

Claims (11)

A pressure chamber forming substrate in which a plurality of pressure chambers for liquid discharge communicating with a plurality of nozzles for discharging liquid are arranged side by side in a predetermined direction.
A diaphragm layer provided on the side opposite to the nozzle side of the pressure chamber forming substrate, and a part thereof constitutes a wall surface of the pressure chamber.
An electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber is provided.
In the pressure chamber forming substrate, a groove having a nozzle-side surface opened is formed on the end side of the pressure chamber in the predetermined direction.
The diaphragm layer on the pressure chamber is formed by bending toward the pressure chamber side.
The diaphragm layer on the groove is formed by bending toward the opening side of the groove .
A liquid discharge head characterized in that the degree of bending of the diaphragm layer of the pressure chamber is larger than the degree of bending of the diaphragm layer of the groove . A pressure chamber forming substrate in which a plurality of pressure chambers for liquid discharge communicating with a plurality of nozzles for discharging liquid are arranged side by side in a predetermined direction.
A diaphragm layer provided on the side opposite to the nozzle side of the pressure chamber forming substrate, and a part thereof constitutes a wall surface of the pressure chamber.
An electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber is provided.
In the pressure chamber forming substrate, a groove having a nozzle-side surface opened is formed on the end side of the pressure chamber in the predetermined direction.
The diaphragm layer on the groove is formed by bending toward the opening side of the groove.
When the degree of bending of the diaphragm layer of the groove is indicated by the radius of curvature R, the radius of curvature R is 2000 μm or more .
A liquid discharge head characterized in that the degree of bending of the diaphragm layer of the pressure chamber is larger than the degree of bending of the diaphragm layer of the groove . The liquid discharge head according to claim 1 or 2 , wherein the first insulating protective film, the wiring layer, and the second insulating protective film are formed in this order on the diaphragm layer on the groove. A pressure chamber forming substrate in which a plurality of pressure chambers for liquid discharge communicating with a plurality of nozzles for discharging liquid are arranged side by side in a predetermined direction.
A diaphragm layer provided on the side opposite to the nozzle side of the pressure chamber forming substrate, and a part thereof constitutes a wall surface of the pressure chamber.
An electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber is provided.
In the pressure chamber forming substrate, a groove having a nozzle-side surface opened is formed on the end side of the pressure chamber in the predetermined direction.
The diaphragm layer on the pressure chamber is formed by bending toward the pressure chamber side.
The diaphragm layer on the groove is formed by bending toward the opening side of the groove.
A liquid discharge head characterized in that a first insulating protective film, a wiring layer, and a second insulating protective film are formed in this order on the diaphragm layer on the groove. A pressure chamber forming substrate in which a plurality of pressure chambers for liquid discharge communicating with a plurality of nozzles for discharging liquid are arranged side by side in a predetermined direction.
A diaphragm layer provided on the side opposite to the nozzle side of the pressure chamber forming substrate, and a part thereof constitutes a wall surface of the pressure chamber.
An electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber is provided.
In the pressure chamber forming substrate, a groove having a nozzle-side surface opened is formed on the end side of the pressure chamber in the predetermined direction.
The diaphragm layer on the groove is formed by bending toward the opening side of the groove.
When the degree of bending of the diaphragm layer of the groove is indicated by the radius of curvature R, the radius of curvature R is 2000 μm or more.
A liquid discharge head characterized in that a first insulating protective film, a wiring layer, and a second insulating protective film are formed in this order on the diaphragm layer on the groove . The liquid discharge head according to claim 4 or 5 , wherein the degree of bending of the diaphragm layer of the pressure chamber is larger than the degree of bending of the diaphragm layer of the groove. The liquid discharge head according to any one of claims 3 to 6, wherein the first insulating protective film and the second insulating protective film are made of a material having tensile stress. The pressure chamber forming substrate is provided with at least one dummy pressure chamber between the pressure chamber and the groove, which does not participate in the discharge of liquid, in the predetermined direction.
The liquid discharge head according to any one of claims 1 to 7 , wherein the diaphragm layer on the dummy pressure chamber is formed by bending toward the dummy pressure chamber side. In the plane of the pressure chamber forming substrate, the predetermined direction is the X direction, the direction orthogonal to the X direction is the Y direction, the size of the groove in the X direction is X1, the size in the Y direction is Y1, and the X of the pressure chamber is X. The liquid discharge head according to any one of claims 1 to 8 , wherein the following formula (1) is satisfied when the size in the direction is X2 and the size in the Y direction is Y2.
X1 ≤ X2 and Y1 <Y2 ... (1) A liquid discharge unit comprising the liquid discharge head according to any one of claims 1 to 9 . A device for discharging a liquid, comprising the liquid discharge head according to any one of claims 1 to 9 or the liquid discharge unit according to claim 10 .

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